Circuit breaker

ABSTRACT

An aircraft circuit breaker in which a push-pull manual operator controls a slidable contact carrier. The contact carrier is controlled by a pair of laterally extending slides which are engaged, respectively, with a current responsive bimetal and an ambient temperature-responsive bimetal. Relative lateral movement of the slides effects disengagement of a latch to permit movement of slidable contact carrier into the contact&#39;&#39;s open position. A manual latch, operated by the push-pull manual operator, is provided which self-disengages when the automatic latch disengages. The manual latch includes a manual latch member which is mounted independently of the temperature-responsive bimetal and a manual latch surface which is supported on the housing independently of the current-responsive bimetal element which is engageable with the latch member to effect a manual latch for maintaining the contacts in a closed condition.

United States Patent [7 2] inventors Dean D. Walling;

Preston D. Rowan, both of Jackson, Mich. [21] Appl. No. 6,264 [22] Filed Jan. 27, 1970 [45] Patented Dec. 21, 1971 [73] Assignee Mechanical Products Jackson, Mich.

[54] CIRCUIT BREAKER 4 Claims, 4 Drawing Figs.

[52] u.s. Cl 337/66 [51] lnt.Cl ..i{01h71/16, HOlh 71/22, HOlh 73/30 [50] Field of Search 337/62, 63, 64, 65, 66

[56] References Cited UNITED STATES PATENTS 3,416,113 12/1968 MacDonald et a1. 337/62 UX 3,287,523 11/1966 MacDonald et a1. 337/62 3,108,164 10/1963 Bullock et a1 337/62 2,952,757 9/1960 Ellenberger 337/62 Primary Examiner-Bernard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney-Harness, Dickey & Pierce ABSTRACT: An aircraft circuit breaker in which a push-pull manual operator controls a slidable contact carrier. The contact carrier is controlled by a pair of laterally extending slides which are engaged, respectively, with a current responsive bimetal and an ambient temperature-responsive bimetal.

. Relative lateral movement of the slides effects disengagement of a latch to permit movement of slidable contact carrier into the contacts open position. A manual latch, operated by the push-pull manual operator, is provided which self-disengages when the automatic latch disengages. The manual latch includes a manual latch member which is mounted independently of the temperature-responsive bimetal and a manual latch surface which is supported on the housing independently of the current-responsive bimetal element which is engageable with the latch member to effect a manual latch for maintaining the contacts in a closed condition.

PATENTED [15021 :97:

SHEET 2 OF. 3

CIRCUIT BREAKER BACKGROUND OF THE INVENTION The instant invention is an improvement over the inventions disclosed in US. Pat. Nos. 3,287,523 and 3,416,113 which are assigned to the assignee of the instant invention, and relates to the invention claimed in the copending application of Dean D. Walling, Ser. No. 4672, entitledCircuit Breaker, also assigned to the assignee of this invention.

SUMMARY OF THE INVENTION The invention lies in the provision of a novel manual latch for a circuit breaker having at least one manual, latching member engaging a cooperating surface directly supported by the housing whereby the bimetals of the circuit breaker are not stressed upon opening of the manual latch. As an additional feature of this invention, a manual latch for a circuit breaker is provided which is self-disengaging upon disengagement of the thermal latch of the circuit breaker whereby the bimetals do not directly act against the manual latch, and consequently, resistance to movement of the bimetals is minimized. The exemplary manual latch according to this invention has a latching member which is resiliently biased toward an unlatched position, but is frictionally retained in a latched position by a force applied thereto through an automatic latch member or clevis which is maintained so long as the thermal latch is engaged.

IN THE DRAWINGS FIG. I is a side elevational view, partially in section, of an improved circuit breaker in accordance with the instant invention with the cover removed therefrom;

FIG. 2 is an exploded view of the manual operator and thermally responsive latch shown in assembly view in FIG. 1;

FIG. 3 is a cross-sectional view taken substantially along the line 3-3 of FIG. 1; and

FIG. 4 is an exploded view of the contacts assembly shown inassembly view in FIG. I.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As best seen in FIG. I, a circuit breaker 10, In accordance with an exemplary constructed embodiment of the instant invention, comprises an enclosure 12 having a pair of terminals 14 and I6 thereon which extend exteriorly of the enclosure 12 for connection to an electrical source. A threaded ferrule 18 extends exteriorly of the enclosure 12 for the guidance of a manual operator 20. The ferrule 18, in conjunction with a nut (not shown), provides a mounting means for the circuit breaker I on a panelboard (not shown).

As best seen in FIG. 2, the manual operator 20 is provided with an end cap 21 and a guide sleeve 22. The manual operator 20 including the end cap 21 and guide sleeve 22 are capable of sliding axial movement with respect to the ferrule I8.

connected to the lower portion of the central sleeve 30 by the pin 41. The manual latching member 42 is provided with a latching surface 44 which is adapted to engage a cooperating latching pin 46 which is supported in a fixed position with respect to ferrule 18 by a groove 48.

The manual latching member 42 has a slot 50 including an upper camming surface 52 which is slightly angulated with respect to the axial motion of the central sleeve 30 and a lower camming surface 53 which is severely angulated with respect to the axial motion of the central sleeve 30 to prevent accidental disengagement of the manual latch upon jarring. The central stem 24 is provided with a camming pin 54 extending across the slot 26 therein and through the slot 50 of the manual latching member 42 so as to be in operative engagement with the camming surface 52.

The second manual latching member 43 is positioned parallel to and contiguous with the first manual latching member 42 to engage a second cooperating latching pin 58 in groove 60. The second manual latching member 43 is also pivotally connected to the pin 41 and has an upper camming surface 61 and a lower camming surface 63 operated by the pin 54 in a manner like that of the first latching member 42.

A spring 62 is provided to resiliently bias the guide sleeve 22 upwardly with respect to the ferrule 18. Consequently, the manual operator 20 and the central stem member 24 are resiliently biased upwardly with respect to the ferrule 18.

Referring now to FIG. 4, a movable contact carrier 64 has a central opening 66 therein for acceptance of the clevis 36. The end portions 67 of the contact carrier 64 cooperate with slides 45 in the housing 12 to guide axial movement thereof as shown in FIG. 3.

The manual operator 20 is also provided with a central stem portion 24 which is fixed to the manual operator end cap 21. The stem member 24 is provided with a central slot 26 extending upwardly approximately half the length thereof. A central sleeve 30 having a slot 32 corresponding to the slot 26 of the central stem 24 is disposed between the guide sleeve 22 and the central stem 24 for sliding axial motion with respect thereto.

The sleeve member 30 is provided with a clevis or thermally releasable latching member 36 formed as shown in the drawings to provide an abutting latch surface 38 and a hook portion 40. The clevis 36 is pivotally connected to the lower portion of the central sleeve 30 by a pin 41.

As can be seen in FIG. 3, the end portions 39 of pin 41 cooperate with grooves 45 in the housing 12 to guide axial movement thereof.

Referring again to FIG. 2, a first and second manual latching members 42 and 43, respectively are also pivotally The contact carrier 64 has a support arm 68 having a pair of movable contacts 70 positioned thereon which is resiliently biased downwardly with respect to the contact carrier 64 by a spring member 71 (FIG. 1). The movable contacts 70 are engageable with fixed contacts 72 to complete a circuit from terminal 14 to terminal 16 through a current-responsive bimetal element of the circuit breaker 10 as shown in FIG. 4.

A helical coil spring 74 (FIG. I) is positioned in a recess 76 of the housing I2 such that it abuts against the housing at one end and the movable contact carrier 64 at its other end so as to normally bias the contact carrier 64 upwardly relative to the housing 12 as seen in FIG. 2.

In accordance with the instant invention, the contact carrier 64 has a laterally extending slot 78 therein for the acceptance of a clevis guide 80 and a latch slide 82. The clevis guide 80 is movable internally of the contact carrier 64 under the influence of an elongated current responsive bimetal 84. More particularly, an end portion 86 of the slide 80 interlocked by a slidable fixture 87 with the current responsive bimetal 84 whereby lateral movement of the slide is controlled by the bimetal. The other end of the clevis guide 80 is provided with a slot 88 which accepts and closely cooperates with the clevis 36 to effect pivoting thereof in response to lateral movement of the slide 80.

The latch slide member 82 abuts the clevis guide 80 and is movable internally of the contact carrier 64 under the influence of an elongated temperature-compensating bimetal 90. The temperature-responsive bimetal 90 is interlocked to an end portion 94 of the latch slide 82 by a slot 92 therein whereby the lateral movement of the slide 82 is controlled by the bimetal. The other end of the latch slide 82 is provided with a slot 96, which, when the circuit breaker is in the contacts closed position, accepts the hooked end 40 of the clevis 36. In the contacts closed position, the latch surface 38 of the clevis 36 abuts the upper surface of the latch slide 82 with a pressure determined by upward resilient bias provided by springs 7 I and 74.

Referring now to FIG. I, the current-responsive bimetal 84 is fixed to the housing 12 at opposite ends as shown. The temperature-responsive bimetal element 90 is fixed in the housing I2 at its lower end and is mounted for lateral adjustment at its upper end to permit calibration of the circuit breaker I0.

The circuit breaker as shown in the drawings is in the contacts closed condition. ln this position, an upwardly acting force is transmitted from the upper surface of latch slide 82 through the clevis 36 to the pin 41. This force causes the latch surfaces of the manual latch members 42 and 43 to bear against the latching pins 46 and 58. As a result, a lateral frictional force is established between the latching surfaces and the latching pins 46 and 58. The lateral frictional force counteracts a laterally inward force provided by the resilient upward bias of the pin 54 against the camming surfaces 52 and 61 so as to prevent a laterally inward motion of the latching members 42 and 43. Upon release of the upward acting force on the latching pins 46 and 58, the camming forces take precedence thereby drawing the latching members 42 and 43 inwardly'to remove the latching surfaces from the latching pins 46 and 58, respectively, and permitting upward motion of the manual operator 20. Therefore, it will be appreciated that the manual latch is self-disengaging upon release of the upward force on the clevis member 36.

Upon occurrence of an overload condition, the center portion of the current responsive bimetal element 84 flexes to the right so as to draw the clevis guide 80 to the right, and consequently, to draw the clevis 36 to the right. Movement of the clevis guide slide 80 to the right pulls the latch surface 38 of the clevis 36 off the latch slide 82 into the opening 96 in the latch slide 82. The force between the latch surface 38 and the upper surface of slide 82 is released permitting upward motion of the contact carrier 64, and consequent disengagement of the contacts 70 and 72, and self-disengagement of the manual latch.

Temperature compensation is achieved through movement of the latch slide 82 with respect to the clevis guide 80 in response to flexing of the center portion of the ambient temperature-responsive bimetal element 90 in accordance with ambient temperature changes. The ambient temperature bimetal element 90 is selected such that increases in ambient temperature causes a movement of the latch slide 82 to the right which is substantially equal to the movement of the clevis guide 80 to the right by virtue of flexing of the current responsive bimetal 84 in response to ambient temperature changes.

Manual disengagement of the contacts 70 and 72 is accomplished by an upward pull on the manual operator which establishes an additional laterally inward force on the manual latching members 42 and 43 due to the additional force of the stem pin 54 on the camming surfaces 52 and 61. In this regard, it can be seen that the slidable relationship of the central sleeve 30 with respect to the central stem 24 provides lost" motion therebetween which permits the above-described camming action.

The contacts may be reengaged by depression of the manual operator 20 to move sleeve 30 downwardly to bring the clevis 36 in engagement with the latch slide 82, and consequently, to bring the contact 70 and 72 into engagement whereupon the manual latch members 42 and 43 move laterally outwardly so as to be in position to engage pins 46 and 58, respectively upon release of the manual operation 20 to maintain the contacts 70 and 72 in the closed position.

As can be seen in the drawings, the thermal latch is accomplished at the abutment between the latch surface 88 of the clevis 36 and the upper surface of the latch slide 82. As a result, neither bimetal element 84 or 90 is subjected to latch loads. Moreover, the manual latching member acts on a member directly supported by the housing rather than on either slide. Hence, the bimetal elements 84 and 90 do not act directly against the manual latch.

lt is to be understood that the specific construction of the improved circuit breaker herein disclosed and described is presented for the purpose of explanation and illustration and is not intended to indicate limits of the invention, the scope of which is defined by the following claims.

What is claimed is:

1. An electrical circuit breaker comprising:

a housing;

a pair of external terminals supported by said housing for connection to a source of electrical current;

an internal fixed contact supported by said housing connected to one of said terminals;

a contact carrier biased from said fixed contact having a movable contact thereon which is movable with respect to said housing to a closed position wherein said movable contact is engaged with said internal contact;

an elongated bimetallic element in said housing electrically connected to the other of said terminals and to said movable contact when said movable contact is engaged with said fixed contact and responsive to current flow therethrough;

a thermal latch connected to a manual operator including a thermal latch member and a thermal latch surface which are engageable to maintain said contact in said closed position, said thermal latch being operatively connected to said current-responsive bimetallic element so as to be controlled by said current-responsive bimetallic element to disengage said thermal latch member and said thermal latch surface in response to movement of said bimetallic element representative of a predetermined current flow therethrough; and

said manual operator connected through said thermal latch to said contact carrier independently of said bimetallic element to move said contact carrier to the contacts closed condition, said manual operator having manual latching means including a manual latch member, means mounting said latch member independently of said current-responsive bimetallic element, and a manual latch surface which is directly supported on said housing independently of said current-responsive bimetallic element and which is engageable with said latching member to effect a manual latch for maintaining said contacts in said closed condition when said thermal latch member is engaged with said thermal latch surface, said manual latch member being resiliently biased to a disengaged position with respect to said latch manual surface so that said manual latch member and said manual latch surface are self-disengaging when said thermal latch disengages.

2. A electrical circuit breaker in accordance with claim I wherein said contact carrier is biased by resilient means;

said resilient means applying a force through said thermal latch member to said latch member to frictionally maintain said manual latch member in a latched position, said resilient means being controlled by said thermal latch such that disengagement of said thermal latch releases said force thereby causing movement of said resiliently biased manual latch member to an unlatched position.

3. An electrical circuit breaker comprising:

a housing;

a pair of external terminals supported by said housing for connection to a source of electrical current;

an internal fixed contact supported by said housing connected to one of said terminals;

a contact carrier biased from said fixed contact having a movable contact thereon which is movable with respect to said housing to a closed position wherein said movable contact is engaged with said internal contact;

an elongated bimetallic element in said housing electrically connected to the other of said terminals and to said movable contact when said movable contact is engaged with said fixed contact and responsive to current flow therethrough;

a thermal latch connected to a manual operator including a thermal latch member and a thermal latch surface which are engageable to maintain said contact in said closed position, said thermal latch being operatively connected to said current-responsive bimetallic element so as to be controlled by said current-responsive bimetallic element to disengage said thermal latch member and said thermal latch surface in response to movement of said bimetallic element representative of a predetermined current flow therethrough; and

said manual operator connected through said thermal latch to said contact carrier independently of said bimetallic element to move said contact carrier to the contacts closed condition, said manual operator having manual latching means including a manual latch member, means mounting said latch member independently of said current-responsive bimetallic element, a manual latch surface which is directly supported on said housing independently of said current-responsive bimetallic element and which is engageable with said latching member to effect a manual latch for maintaining said contacts in said closed condition when said thermal latch member is engaged with said thermal latch surface said manual latch member being resiliently biased to a disengaged position with respect to said manual latch surface, said thermal latch member being connected to said manual latch member for applying a force to said manual latch member for maintaining said manual latch member in engagement with said manual latch surface by frictional engagement therewith, and means intermediate said manual latch member and said housing through which said force maintaining said latch member in engagement with said manual latch surface is applied to said housing with said means being adapted so that'said force is applied between said manual latch member and said housing substantially without being applied to said bimetallic element, said manual latch member being controlled by said thermal latch to remove said force applied through said intermediate means when said thermal latch disengages so that said manual latch member and said manual latch surface are self-disengaging when said thermal latch disengages. 4. An electrical circuit breaker in accordance with claim 3 wherein said manual latching means further includes a second manual latch member which is mounted independently of said current-responsive bimetallic element and a second manual latch surface which is directly supported on said housing independently of said current-responsive bimetallic element and which is engageable with said second latching member to effect a second manual latch for maintaining said contacts in said closed condition when said thermal latch is engaged, said second manual latch member being resiliently biased to a disengaged position with respect to said second manual latch surface, said thermal latch member being also connected to said second manual latch member for applying a force to said second manual latch member for maintaining said second manual latch member in engagement with said second manual latch surface by frictional engagement therewith, said second manual latch member being controlled'by said thermal latch to remove said force applied to said second latch surface when said thermal latch disengages so that said second latch is selfdisengaging when said thermal latch disengages. 

1. An electrical circuit breaker comprising: a housing; a pair of external terminals supported by said housing for connection to a source of electrical current; an internal fixed contact supported by said housing connected to one of said terminals; a contact carrier biased from said fixed contact having a movable contact thereon which is movable with respect to said housing to a closed position wherein said movable contact is engaged with said internal contact; an elongated bimetallic element in said housing electrically connected to the other of said terminals and to said movable contact when said movable contact is engaged with said fixed contact and responsive to current flow therethrough; a thermal latch connected to a manual operator including a thermal latch member and a thermal latch surface which are engageable to maintain said contact in said closed position, said thermal latch being operatively connected to said currentresponsive bimetallic element so as to be controlled by said current-responsive bimetallic element to disengage said thermal latch member and said thermal latch surface in response to movement of said bimetallic element representative of a predetermined current flow therethrough; and said manual operator connected through said thermal latch to said contact carrier independently of said bimetallic element to move said contact carrier to the contacts closed condition, said manual operator having manual latching means including a manual latch member, means mounting said latch member independently of said current-responsive bimetallic element, and a manual latch surface which is directly supported on said housing independently of said current-responsive bimetallic element and which is engageable with said latching member to effect a manual latch for maintaining said contacts in said closed condition when said thermal latch member is engaged with said thermal latch surface, said manual latch member being resiliently biased to a disengaged position with respect to said latch manual surface so that said manual latch member and said manual latch surface are self-disengaging when said thermal latch disengages.
 2. A electrical circuit breaker in accordance with claim 1 wherein said contact carrier is biased by resilient means; said resilient means applying a force through said thermal latch member to said latch member to frictionally maintain said manual latch member in a latched position, said resilient means being contrOlled by said thermal latch such that disengagement of said thermal latch releases said force thereby causing movement of said resiliently biased manual latch member to an unlatched position.
 3. An electrical circuit breaker comprising: a housing; a pair of external terminals supported by said housing for connection to a source of electrical current; an internal fixed contact supported by said housing connected to one of said terminals; a contact carrier biased from said fixed contact having a movable contact thereon which is movable with respect to said housing to a closed position wherein said movable contact is engaged with said internal contact; an elongated bimetallic element in said housing electrically connected to the other of said terminals and to said movable contact when said movable contact is engaged with said fixed contact and responsive to current flow therethrough; a thermal latch connected to a manual operator including a thermal latch member and a thermal latch surface which are engageable to maintain said contact in said closed position, said thermal latch being operatively connected to said current-responsive bimetallic element so as to be controlled by said current-responsive bimetallic element to disengage said thermal latch member and said thermal latch surface in response to movement of said bimetallic element representative of a predetermined current flow therethrough; and said manual operator connected through said thermal latch to said contact carrier independently of said bimetallic element to move said contact carrier to the contacts closed condition, said manual operator having manual latching means including a manual latch member, means mounting said latch member independently of said current-responsive bimetallic element, a manual latch surface which is directly supported on said housing independently of said current-responsive bimetallic element and which is engageable with said latching member to effect a manual latch for maintaining said contacts in said closed condition when said thermal latch member is engaged with said thermal latch surface said manual latch member being resiliently biased to a disengaged position with respect to said manual latch surface, said thermal latch member being connected to said manual latch member for applying a force to said manual latch member for maintaining said manual latch member in engagement with said manual latch surface by frictional engagement therewith, and means intermediate said manual latch member and said housing through which said force maintaining said latch member in engagement with said manual latch surface is applied to said housing with said means being adapted so that said force is applied between said manual latch member and said housing substantially without being applied to said bimetallic element, said manual latch member being controlled by said thermal latch to remove said force applied through said intermediate means when said thermal latch disengages so that said manual latch member and said manual latch surface are self-disengaging when said thermal latch disengages.
 4. An electrical circuit breaker in accordance with claim 3 wherein said manual latching means further includes a second manual latch member which is mounted independently of said current-responsive bimetallic element and a second manual latch surface which is directly supported on said housing independently of said current-responsive bimetallic element and which is engageable with said second latching member to effect a second manual latch for maintaining said contacts in said closed condition when said thermal latch is engaged, said second manual latch member being resiliently biased to a disengaged position with respect to said second manual latch surface, said thermal latch member being also connected to said second manual latch member for applying a force to said second manual latch member for maintaining said second manual latch member in engagement with said second manUal latch surface by frictional engagement therewith, said second manual latch member being controlled by said thermal latch to remove said force applied to said second latch surface when said thermal latch disengages so that said second latch is self-disengaging when said thermal latch disengages. 